点击次数：

论文类型：期刊论文

发表时间：2019-09-02

发表刊物：CHEMBIOCHEM

收录刊物：SCIE

卷号：20

期号：17

页面范围：2241-2247

ISSN号：1439-4227

关键字：aptamers; biosensors; DNA; fluorescence; sodium

摘要：Fluorescent metal sensors based on DNA often rely on changes in end-to-end distance or local environmental near fluorophore labels. Because metal ions can also nonspecifically interact with DNA through various mechanisms, such as charge screening, base binding, and increase or decrease in duplex stability, robust and specific sensing of metal ions has been quite challenging. In this work, a side-by-side comparison of two signaling strategies on a Na+-specific DNAzyme that contained a Na+-binding aptamer was performed. The duplex regions of the DNAzyme was systematically shortened and its effect was studied by using a 2-aminopurine (2AP)-labeled substrate strand. Na+ binding affected the local environmental of the 2AP label and increased its fluorescence. A synergistic process of Na+ binding and forming the duplex on the 5 '-end of the enzyme strand was observed, and this end was close to the aptamer loop. Effective Na+ binding was achieved with a five base-pair stem. The effect on the 3 '-end is more continuous, and the stem needs to form first before Na+ can bind. With an optimized substrate binding arm, a FRET-based sensor has been designed by labeling the two ends of a cis form of the DNAzyme with two fluorophores. In this case, Na+ failed to show a distinct difference from that of Li+ or K+; thus indicating that probing changes to the local environment allows more robust sensing of metal ions.